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Old May 31, 2008, 07:22 PM
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Shake Down Cruise

Took my USS Wainwright out for her maiden/shake down cruise today. Had to add 5 lbs of weight to her to get her to sit right. Had a problem with the balance on it. I would add the bridge to it and no matter what we would do it would tip over. We would get it close to balanced but it would never right itself. Moved weights all over the place inside but didnt help. I was thinking that the bilge keels need to be bigger. I made them as according to plans which is about 1/2" wide. I was thinking of extending them out to 2" to give the boat more balance. Does this sound like a good solution or am I doing something else wrong? I know it wont be scale but at least she wont tip over. Suggestions?
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Old May 31, 2008, 08:01 PM
Veni, Vidi, Feci
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Nope, bilge keels won't help a bit... unless they're made of lead!
Bilge keels are dynamic devices- they offer more resistance to heeling the faster the hull heels (or rolls)... but if the hull wants to tip over just sitting there (a slow roll), the bilge keels will do nothing.

This type of hull is tippy in the best circumstances, but they can be set steady in the water... they just require ultra light topsides, with the vast majority of the weight down low.

If all else fails, ballast her heavy, and paint the waterline a bit higher! That will help.
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Old May 31, 2008, 08:02 PM
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BIKERIDER- I donít think the bilge keels are going to help you with the balance problem. Bilge keels by nature are for slowing the roll of the hull abeam, not for righting the hull. I think you have an issue with the superstructure being to heavy in that it changes the center of gravity on the hull when put in place. The only way to correct the problem is to lighten the superstructure or relocate the added 5 lbs of weight you said you added directly to the bottom of the hull and spread out to get as low as possible in the whole length of the hull.
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Old May 31, 2008, 08:28 PM
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Thanks for the help guys!! The bilge keel was just a thought, wasnt sure if it would work or not thats why I turned to the "experts". I think I will just rebuild the bridge using foam and fiberglass. I can transfer some fittings over and buy new ones that dont transfer. Foam should make it nice and lite. Thanks again guys!
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Old May 31, 2008, 10:30 PM
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Some years ago I built the Dumas USS Crockett, which was a long narrow hull. I remember in the documentation they said how they needed to trim weight topside. That was interesting in that they supplied white metal 50 cals that were too large (almost as big as the 40 mm) which were mounted on the bridge deck. I dumped them for some scavenged plastic ones of a Lindberg PT and that saved a lot of weight. I kept the motors and batteries as low in the hull as possible. Any weight you can get down to the keel will help. If you have a good handle on the amount of ballast you need try BB's along the keel. You can set it with epoxy, carpenters glue, or paraffin wax. Boater Dave used wax to set ballast in some Fairwind sailboats and said it worked good. If you can lose any metal from the superstructure in favor of plastic it will help too. The weight you cut high is shifted down low so you get double effect.
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Old Jun 01, 2008, 11:42 AM
r/c ships and workboats
bellingham, wa
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That is one of the main issues with Navel vessels that are long and skinny ( compared to a battleship or tug). Top weight is the main reason that models of desroyers and cruisers ( modern) have a tendency to heal in turns or in less than smooth water surfaces. Remove as much unwanted weight in the supper structure ( areas under the house where flooring will not be seen or used) as possible. Rebuild parts out of lighter material if nessasary. Don't be disscourage, just look for weight savings.
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Old Jun 01, 2008, 12:22 PM
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Joined Dec 2002
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The top of my 1/72nd scale destroyer is built up of 1/32nd- 1/16th inch thick
plywood decks and uses pink foam as spacers(floor-ceiling height).
The structures are sheeted with balsa. All of this is to keep the top sides
as light as possible. There is no problem sitting upright, but sharp turns will
heel the boat over hard.

One of the smaller 1/72nd German T-boats was nick named
the "Infamous German Wiggle ship", as every time it made a turn it would
wobble back and forth till it settled on an even keel.

Drilling or cutting lightening holes in the supersturcture plates and framing would
be my first suggestion.
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Old Jun 01, 2008, 12:40 PM
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The bigger the model, the easier it gets... and if Umi has a challenge in 1:72, it won't be easier in 1:96!
Most 1:96 Burkes etc. I've seen are tipsy to the point that I'd consider a "hidden" keel with a lead bulb if I ever took one on.
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Old Jun 01, 2008, 04:00 PM
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As Patmat sugested,take your 5 lbs of lead off, make a detachable metal keel 6 or 8 '' long with that 5 lbs mounted to the bottom end of it. It would still float at the waterline but with much lower center of balance. Much less role. Much more stable.
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Old Jun 02, 2008, 08:10 AM
Retired for now
Bonita Springs,Fl.
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The Dumas Tuna CLipper has the same problem with the tuna tower on it. Built like Dumas says, it's really top heavy. You just have to keep adding weight down in the hull as low as you can get it until it sets right or sinks. Problem solved. Ha! Pete
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Old Jun 02, 2008, 10:54 AM
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Quote:
Originally Posted by frankg
BIKERIDER- I donít think the bilge keels are going to help you with the balance problem. Bilge keels by nature are for slowing the roll of the hull abeam, not for righting the hull. I think you have an issue with the superstructure being to heavy in that it changes the center of gravity on the hull when put in place. The only way to correct the problem is to lighten the superstructure or relocate the added 5 lbs of weight you said you added directly to the bottom of the hull and spread out to get as low as possible in the whole length of the hull.
I have the same issue with Nord Icelandia. one idea that I have thaught of, is a pair of horizontal fins on the rudder angled downwards, so as the ship heels to starboard during a turn to port, water flow is directed downwards, pushing starboard side UP.

another option, bend the rudders outwards. the carrier, USS enterprise has rudders tilted out so that the propwash from the outboard engine was deflected downwards to force the ship to level

option 2 - yacht keel
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